Measuring system

ABSTRACT

Dimensional measurement of a pattern is achieved by televising the pattern and displaying the pattern on a television monitor. A special effect or measuring raster is generated and superimposed upon the pattern in such a manner that the raster overlaps at least one dimension of the pattern to be measured. By means of a suitable pulse generator and gating circuit, a series of uniformly timed pulses are produced in timed response to the coincidence of (a) the video signal of the pattern exceeding a fixed threshold value, and (b) the electronic waveform representing the special effect raster exceeding a nominal value. Periodically, the pulses produced are counted and numerical value commensurate therewith is displayed.

United States Patent [451 July 25, 1972 Montone [54] MEASURING SYSTEM[72] Inventor: Liber J. Montone, Reading, Pa.

[73] Assignee: Western Electric Company, Incorporated,

New York, NY.

[22] Filed: Jan. 19, 1970 211 App]. No.: 3,628

[52] U.S.Cl..... ..l78/6, l78/DIG. 36 [51] Int. Cl. ..H04n 7/02 [58]Field of Search ..l78/6, DIG. 21, DIG. l, 68

[56] References Cited UNITED STATES PATENTS 3,244,810 4/1966 Williams..178/6.8 3,390,229 6/1968 Williams ..178/6 3,449,511 6/1969 Hecker..178/DIG. 1 2,774,964 12/1956 Baker et a1 ..178/DIG. 21

3,321,575 5/1967 Lewczyk ..178/DlG. 1

Primary Examiner-Robert L. Grifiin Assistant Examiner-Barry LeibonitzAttorney-W. M. Kain, R. P. Miller and R. Y. Peters [57] ABSTRACTDimensional measurement of a pattern is achieved by televis ing thepattern and displaying the pattern on a television monitor. A specialeffect or measuring raster is generated and superimposed upon thepattern in such a manner that the raster overlaps at least one dimensionof the pattern to be measured. By means of a suitable pulse generatorand gating circuit, a series of uniformly timed pulses are produced intimed response to the coincidence of (a) the video signal of the patternexceeding a fixed threshold value, and (b) the electronic waveformrepresenting the special effect raster exceeding a nominal value.Periodically, the pulses produced are counted and numerical valuecommensurate therewith is displayed.

7 Claims, 15 Drawing Figures L L 1 A 34a, .4... L. I VARIABLE PULSEVARIABLE PULSE NAND L vARIA ILE PuLs VARIA LE PULSE" I WIDTH "ONESHOTWIDTH 'oNE sHoT' wIoTH ONE SHOT WIDTH ONE SHOT MULTIVIBRATORMULTIVIBRATOR GATE MULTIVIBRATOR MULTIVIBRATOR I I p/4V 32 33 341r 35 W8 39 l I TOP BOTTOM LEFT RIGHT I l l I HORIZONTAL I SYNCDELAY I I 37 I IA A LL L n L L L L ..I

26-" i HOR.DEFL.

20 2 VERT. DEFL. 1 l8 I7 22 It VERTICAL HORIZONTAL i 2W9". 2 a 25 24 Tv-CAMERA {VIDEO I9 RESET COUNTER DlGITAL PULSE PATENTEDJULZS I972 3.679B20 SHEET 2 0F 3 SPECIAL EEEECTS 1 SWITCHER CENERATOR EADER MONITOR H vH 83- SYNC- OEN. V

i l v TELEVISION GATE ULSE COUNT, CAMERA GENERATOR I as 67 as MEASURINGSYSTEM BACKGROUND OF THE INVENTION This invention relates to the fieldof metrology, and in particular to the objective measurement ofdimensions of microscopic geometries which are displayed on a televisionmonitor which receives its signals from a television camera microscope.Accordingly, the general objects of the invention are to provide new andimproved apparatus and methods of such character.

In the design of very small devices, such as integrated circuits and themasks used in the manufacture of these circuits, it is desirable todimensionally measure up to hundreds of microscopic odd shapedconfigurations for each individual device. It is further desirable toquickly and accurately determine areas as well as linear dimensions ofirregular shaped patterns of masks. Prior art techniques, in general,have been very inefi'ective in the low cost, quick and accuratemeasurement of specific geometries.

An integrated circuit, typically, may measure 0.0025 square inches,including as many as 100 individual transistors and 100 individualresistors thereon. For accurate alignment, small microscopic T-shapedmarks are used on the individual masks, wherein the width of thevertical stroke of the T shaped mark is approximately 200 microinches.Preferably, it is desirable to be able to measure to a repeatability ofwithin 2 or 3 microinches, in order to manufacture integrated circuitsefficiently on a production line basis.

A typical mask for integrated circuits includes, what appears to be,about 500 tiny dots. Each dot is a complete integrated circuit. Theintegrated circuits are formed from a single semiconductor wafer so thatone wafer yields about 500 circuits. Each integrated circuit may includehundreds of geometries, for example, 100 transistors and 100 resistors.

As many as seven masks (each one with different details) are used inmanufacture of integrated circuits. Because these masks are used asoverlays, it is important that the dimensions, as well as location, ofthe various geometries be extremely accurate so that the masks may besuperpositioned on top of each other at various stages of manufacturingoperations.

Optical measurement may appear proper to the unaided eye. A pair ofapproximately parallel lines may appear parallel to the eye, while infact a small taper exists. In the past, it was necessary to slowly andtediously examine an article under a microscope, align the cross-hairs,turn a micrometer wheel, and read the indicator wheel. It was difficultto find or determine the edge of a pattern with accuracy. Themeasurement of small dimensions, in the past, was highly subjective andinaccurate.

Thus, it is an object of this invention to provide a novel method andapparatus for quickly and objectively measuring dimensions.

A particular object of this invention is to provide a novel method andapparatus for accurately measuring linear and area dimensions ofmicroscopic patterns.

A semiconductor target, used as a component in a television camera tube,measures one-half inch by one-half inch in surface area, and has 840,000tiny diodes 6 microns (or 236 microinches) in width oriented along thesurface area. The size of these diodes varies appreciably, more than i20 microinches, so that uneven shadings are apparent across the face asviewed microscopically. Hence, it is desirable to rapidly measure the840,000 diodes on the semiconductor target. Thus, another object of thisinvention is to provide novel methods and apparatus for rapidlymeasuring the diodes of a semiconductor target.

By practicing the teachings of this invention, the subjectiveness istaken out of measurement by placing the numerical value of themeasurement on a counter which can be easily read. The dimension of thepattern to be measured is converted into a series of pulses which can becounted. Two important advances are achieved: first, the subjectivenessis taken out of the measurement; second, measurements are obtained tothe millionths of an inch.

In the field of medical diagnosis, a Papp Test is often used todetermine the size of cells, since malignant cells are usually largerthan normal. In a typical Papp Test, a glass slide is smeared withthousands of cells. A trained diagnostician carefully and meticulouslyvisually examines the cells. Such examination of cells is difificult inmarginal cases. Cells smaller than a standard may represent normal,non-malignant cells. Large readings may indicate an abnormal cell. Thenormal cell, however, is not standard for all people; it varies fromperson to person, and it may vary within the same person. It should becalibrated for each individual, by known techniques such as by obtaininga smear, a strain, or an equivalent from within the body.

Thus, another object of this invention is to provide a novel method andapparatus for accurately comparing the area measurements of similarmicroscopic patterns against a standard.

SUMMARY OF THE INVENTION In accordance with one embodiment of thisinvention, dimensional measurement of a pattern can be performed bytelevising the pattern, and displaying the pattern on a televisionmonitor. A special effect or measuring raster, generated andsuperimposed on the monitor, is varied so that it overlaps at least onedimension of the pattern to be measured. A series of uniformly timedpulses are produced in response to the coincidence of video informationof the pattern exceeding a fixed threshold value, with the electronicwaveform representing the special effect raster exceeding a nominalvalue. The pulses that are produced are counted during an integralnumber of frames.

In a preferred embodiment, the special effect raster has controllabletop, bottom, left, and right margins.

In one mode, for area measurement, a special effect raster is producedso as to overlap the entire area of the pattern to be measured.

In accordance with a more specific embodiment of the invention, thespecial effect raster can be effectuated by coupling a verticalsynchronizing signal to an input of a first variable pulse widthone-shot multivibrator; coupling the output of the first multivibratorto an input of a second variable pulse width one-shot multivibrator;coupling the output of the second multivibrator to one input of an ANDgate which has its second input coupled to receive a horizontalsynchronization signal; coupling the output of the AND gate to an inputof a third variable pulse width one-shot multivibrator; coupling theoutput of the third multivibrator to an input of a fourth variable pulsewidth one-shot multivibrator; and combining the output of the fourthmultivibrator with the composite video signal and coupling thecombination thereof to a cathode-ray tube.

Apparatus for dimensional measurement, in accordance with an embodimentof this invention, includes a television camera for generating a videosignal of an object to be viewed together with appropriate horizontaland vertical synchronizing signals. Facilities are provided for couplingthe signal from a special effect raster generator, which provides acontrolled raster as to its four margins, together with the video signalgenerated by the television camera, through to the video electrode of acathode-ray tube. The signals from the special effect generator and thetelevision camera are coupled to two input tenninals of an AND gate.Suitable means are coupled to the output of the AND gate for measuringthe duration of the output over an integral number of frames.

In a more specific embodiment of the invention, the measuring meanscoupled to the output of the AND gate includes a resettable digitalpulse counter. The output of the AND gate is coupled to the digitalpulse counter via a pulse generator which generates a plurality ofuniformly timed pulses upon application of an energizing signal to theinput thereof.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of theinvention will become apparent from the following detailed descriptionand the accompanying drawings illustrating specific embodiments thereof,in which:

FIG. I is an electrical block diagram of one embodiment of thisinvention;

FIG. 2 is a display of patterns on the face of a cathode-ray tube, suchdisplay being shown to illustrate the principles of this invention;

FIGS. 3(a) through 3(g) and 3(6) through 3(J constitute a set ofwaveforms, wherein FIGS. 3(a) through (3) are depicted on the same timescale; FIG. 3(G) corresponds to FIG. 3( g) but on a greatly enlargedtime scale; and FIGS. 3(G) through (J) are each depicted on a commontime scale;

FIG. 4 is a display of circular configurations displayed on the face ofa cathode-ray tube, such display being shown to il lustrate otherprinciples of the invention; and

FIG. 5 is a block diagram of alternative circuits for carrying out someof the teachings of this invention.

GENERAL DESCRIPTION In general, special effect, in the television field,has

generally been limited to various television tricks other than thenormal display of a simple scene. In the past, special effects haveincluded such techniques as split screen, corner insert, superpositionof one scene on another scene, the superposition of a portion of onescene onto a complete second scene, etc. As used herein the term specialeffect" or measuring raster generator is to be broadly construed, andincludes, by way of example and not by way of limitation, devices ormeans for producing a signal having a variable pattern as to top,bottom, left, and right or combinations thereof which may be positionedon any part of the display screen.

Referring to FIG. I, there is illustrated apparatus for measuring thelinear and area dimensions of a shaped configuration of a microscopicarticle 11. As shown, the article 1 l to be measured can be placed upona table 12 or other suitable substrate. The article 11 is viewed, via amicroscope 13, by a television camera 14.

The television camera 14, of a type commercially available, has videocircuitry 16 together with horizontal and vertical synchronizationcircuits 17 and 18 associated therewith (in addition to its own powersupply).

The video portion 16 of the television camera 14 is coupled, via a line19, to one input terminal 200 of an isolating circuit, such as a mixer21, the output terminal 22 of which is coupled toa video electrode 23 ofa cathode-ray tube 24.

The horizontal and vertical synchronizing circuits l7 and 18 of thetelevision camera [4 control a special effect raster generator 26 whichis coupled to a second input terminal 20b of the mixer 21 so that theoutput terminal 22 of the mixer 21 provides an electrical signalincluding the composite video signal of the article ll having a specialeffect raster superimposed thereon.

The output from the special effect raster generator 26 is coupled to oneinput terminal 27a of an AND gate 28 having its other input terminal 27bcoupled to the line 19 to receive the video signal of the article 11.The output from the AND gate 28, when on", is coupled to initiate thegeneration of a train of uniformly timed pulses from a variablefrequency pulse generator 29. The variable frequency pulse generator 29is coupled to a digital pulse counter 31.

The digital pulse counter 31 displays the total count of the pulsescoupled thereto by the pulse generator 29. The counter 31 isperiodically reset at frequent intervals, such as, for example, everygiven integral number of frames of video information scanned by thecamera 14.

The Special Effect Raster The special effect raster, in one form ofoperation, may be a brighter than background rectangular pattern,controllable in its four dimensions as to top, bottom, left, and rightboundaries as to its placement on the cathode-ray tube 24.Alternatively, if desired, the raster may be adjusted so that it appearsdarker than background.

The special effect raster generator 26, in one embodiment. as shown inFIG. 1 includes two variable pulse width one-shot multivibrators 32 and33 serially connected from the vertical synchronization circuit 18 ofthe television camera 14 to an input 340 of a NAND gate 35, having asecond input 34b thereof controlled by the output of the horizontalsynchronizing circuit 17. In a particular embodiment, a horizontal syncdelay circuit 37 is inserted between the horizontal synchronizingcircuit 17 and the NAND-gate 35 to provide for better stabilization.

The output of the NAND-gate 35 is coupled through two additionalserially connected variable pulse width one-shot multivibrators 38 and39 to provide the output for the special effect raster generator 26 tothe mixer 21 and the gate 28.

The variable pulse width one-shot multivibrators 32, 33, 38 and 39 usedto generate the special effect raster are standard multivibrators inthat each of them produces an output upon the initiation of a trailingedge of an input signal applied thereto. A one-shot multivibrator, alsoknown as a monostable multivibrator or as a delay flop, is characterizedby the fact that it produces a pulse upon the application of an inputsignal. In the particular instance described, the output pulse widthfrom the multivibrator can vary by adjusting a rheostat. It is desirablethat the multivibrators described herein be adjustable from a fewmicroseconds to a few milliseconds, so

that the special effect raster on a frame of video information can bevaried in every dimension. The timing is somewhat critical since oneframe of video information, as used in commercial television systems,has a 1/30 second duration. Also, there are 525 lines per frame. Thus,it is easily calculated that each line of video information occurs in l/1 5,750 second. Expressed another way, each line of video informationoccurs at approximately 63.5 microseconds.

The Pulse Counting Circuits The output of the special effect rastergenerator 26 and the video signal from the television camera 14 (aftersuitable shaping) are coupled through the AND gate 28, which providesonly the pulse or pulses that are desired to be measured in terms ofpulse width.

As illustrated in FIG. 1, the apparatus is adapted to count or measurethe width or area of a particular shaped configuration, as desired.

Operation Referring to FIG. 2, there are shown, for example, severalpatterns on the surface of an article, including a square 40, a circle41, a letter T 42, and a rectangular bar 43.

Assume it is desired to accurately measure the width of the verticalstructure 46 of the T 42. This can be achieved as follows:

Place the article 11 under consideration within the field of view of thetelevision camera 14 so that the pattern appears on the televisionscreen 47 of the cathode-ray tube 24 as shown in FIG. 2. Next, thespecial effect raster generator 26 (FIG. I) is adjusted so that theleftmost margin of a special effect raster 45 appears just to the leftof the vertical structure 46 of the T 42 and the righthand marginappears just to the right of the vertical structure 46 of the T 42.

In one embodiment, a total of two horizontal lines, desirably, arescanned so as to self-average the width of the vertical structure 46 atthe location being measured.

Referring to FIG. 3 there is shown a series of waveforms (a) through(g), along a common time scale, and a series of waveforms (G) through(J), along an expanded time scale. The waveform at (a) illustrates awaveform of vertical synchronizing pulses from the circuit 18. Thevertical synchronizing pulses occur once every one-sixtieth second andare of short duration. The trailing edge 50 of a vertical synchronizingpulse 51 causes the first one-shot multivibrator 32 to be activated and,as shown in FIG. 3(b), the waveform of the first one-shot multivibratorbecomes positive going, at 52,

' substantially with the trailing edge 50 of the vertical of itsvariable control. At the conclusion of the time period, the voltagelevel of the first multivibrator 32 drops at 53 to its original level,and remains there until, at a subsequent frame, the trailing edge of thesubsequent vertical synchronizing pulse reactivates the multivibrator32.

The trailing edge 53 of the pulse generated by the first oneshotmultivibrator 32 causes the second one-shot multivibrator to beenergized, and, hence, as shown in FIG. 3(c) the output of the secondone-shot multivibrator 33 increases at 54 to a positive level 56 andremains there for a period of time determined by the setting of thevariable control of the second one-shot multivibrator 33. The waveformthen trails at 57 back to its base level and remains there until thesubsequent frame.

FIG. 3(d) illustrates a series of horizontal synchronizing pulses 58-58from the horizontal sync delay circuit 37. As depicted, a limited numberare shown. However, a total of 525 horizontal pulses are normallypresent during every two vertical synchronizing pulses, as is true incommercial television systems. FIG. 3(2) illustrates two negative pulses59-59 from NAND gate 35 which coincide in time with those two horizontalsynchronizing pulses 58-58 which occur during the duration of a positiveoutput level 56 from the second one-shot multivibrator 33. Hence, by theappropriate setting of the controls for the first and second one-shotmultivibrators 32 and 33 the top and bottom boundaries of the specialeffect raster 45 are determined, or expressed another way, the topboundary of the special effect raster is determined together with thenumber of horizontal lines to be scanned.

The negative going pulses 59-59 from the output of the NAND-gate 35initiate output signals of positive pulses 60 60 from the third one-shotmultivibrator 38. The duration of these output signals can be varied bya control of the third multivibrator 38.

The output of the third one-shot multivibrator 38 is coupled to thefourth one-shot multivibrator 39 so that the trailing edge 61 of theoutput signal 60 from the third one-shot multivibrator 38 initiates theactuation of the fourth one-shot multivibrator 39, see FIGS. 30) and3(g). The duration of the pulse 62 generated by the fourth one-shotmultivibrator 39 is variable so as to adjust the rightmost boundary.Thus, FIG. 3(g) illustrates two pulses, designating the boundary of thespecial effect raster 45 that is generated, per frame.

FIG. 3(G) is identical to FIG. 3(g) except that is is greatly expandeddue to the stretching of the time scale.

FIG. 3(H) is a composite video signal of the two complete horizontallines under consideration. The composite video signal includes twohorizontal synchronizing pulses 6363 together with video information forthose two lines including pulses 140, 141, 142 and 143, representingportions of the square 40, circle 41, T 42, and rectangle 43,respectively, shown in FIG. 2.

The output of the AND gate 28 produces pulses 66-66 as shown in FIG.3(I), which corresponds in time, solely to the width of the verticalstructure 46 of the T 42 under consideratron.

The output pulse 66 of the gate 28 is coupled to the pulse generator 29which produces high frequency pulses 6767 for the duration of the pulse66 applied thereto. These pulses 6767 are then directed to the digitalpulse counter 31 which counts the pulses 6767. As viewed in FIG. 3(1),there is shown a plurality of pulses 6767 which occur during the timeintervals of each of the positive pulses 66-66 of FIG. 3(I). The pulses6767, counted by the digital pulse counter 31, are indicative of thewidth of the vertical structure 46 of the T 42.

Referring to FIG. 4, there is shown a television monitor representation151 of a plurality of circular configurations 152, 153, 154 and 155. Thecircular configurations l52-155 may be fixed circular dots, as diodes ona target slice used in a television camera tube. Alternatively, the dotsmay include such generally circularly spaced configurations as livingtissue cells, such as blood cells and the like, wherein it may bedesired to measure the area of the cells to determine their morbidity.

As shown in FIG. 4, the circular configuration 154 to be measured forits area is entirely encompassed by a special effect raster 157 tocompletely cover its top, bottom, left, and right margins without,however, overlapping any adjacent configurations. The area of thecircular configuration 154 is read directly from the digital pulsecounter 31 after applying a factor for the dimension to pulse ratiothereto.

For ease in measurement, it is desirable that the dimension to pulseratio be a convenient multiple that an operator can use. Ideally, a oneto one relationship is preferred. For example, for measuring the widthof a vertical structure of the T (which is a common practice within themanufacture of integrated circuits), the width of such a T may normallybe in the neighborhood of 240 microinches. Hence, it is desirable thatthe counter be directly translatable into microinches so that thecounter itself reads 240. This can be adjusted by using an appropriatepulse source having a frequency of such a value which, together with themagnifying capability of the television microscopic optics, produces amultiplication factor of one to one.

Calibration is performed by varying the frequency of the pulsegenerator. If a standard length is known to be 50 microinches, thefrequency of the pulse generator can be varied so that the counter reads50.

To calibrate, a known standard of similar geometry to the pattern to bemeasured is used. Thus, if it is desired to measure the area of acircle, then a circle of known size is used for calibration. Desirably,if a rectangle is to be measured, then a standard rectangle would beused for calibration. No difference in measuring the area of a rectanglewas observed when the rectangle was scanned along its length comparedwith scanning along its width, with rectangles having aspect ratios lessthan 10:].

A random interlace is desired. This occurs as a normal wobble in the 60cycle line, causing the lines to constantly move. Efiectively, randominterlacing is caused by letting the vertical oscillation freely run,letting the inherent variables within take over. Thus, a line wouldnormally wobble the distance between two lines. A commercial televisioncamera has both random interlace and odd-even interlace settings. Withrandom interlace, the scanned lines are not precisely placed on thescreen. In a sense, an odd-even random interlace takes place. The actionis not precisely fixed; a raking or combing action is obtained. This isvery desirable because the lines are not in the same place and one cansee underneath them. Such random odd-even interlace action can beestablished within a commercially available television camera withoutmodification.

The digital pulse counter is reset periodically, preferably everyintegral number of fields or frames of video information. For example,by resetting every one-tenth second or every full second, eachmeasurement, in effect, is read 6 or 60 times, respectively, yielding acumulative average which statistically works well by providing greateraccuracy in measurement. Ideally, the counter is reset every I0 framesof video information, so that, to read the counter, the observer merelydisregards the last digit (i.e., divides by ten).

Various modifications will be apparent to those skilled in the artwithout departing from the spirit and scope of this invention. Forexample, although horizontal and vertical deflection yokes are depictedin conjunction with the cathode-ray tube 24, it is obvious thatelectrostatic deflection plates can be used in lieu thereof.Furthermore, although a microscope 13 is depicted in the drawings asbeing the preferred mode of practicing this invention, it is notabsolutely necessary to the practice thereof. Also, it will be apparentto those skilled in the art that in lieu of monochromatic tube and amixer as shown in FIG. 1, a multi-gricl, polychromatic cathode-ray tubecan be used in which the mixing takes place within such a polychromatictube. It is intended that this invention be construed broadly to includesuch variations as mixing within a tube itself.

A special effect raster generating means is illustrated Still anothermodification which sacrifices raster mobility that will become apparentto those skilled in the art, without departing from the spirit and scopeof this invention, is a circuit as shown in FIG. including a pluralityof commercially available components: A standard television camera 81and a special effects generator 82 (such as Model SE-l0l-3S sold byShibaden Corporation of America) are coupled together, with a commonhorizontal and vertical synchronizing source 83, to a switcher-fader 84(such as Model VM-l04 sold by Shibaden Corporation of America) to astandard television monitor 85.

The outputs of the television camera 81 and special effect generator 82,together with the H and V outputs of the synchronizing source 83, arecoupled to a gate 86 which provides an output only when there is acoincidence of enabling outputs from the camera 81 and generator 82together with an absence of sync pulses from the synchronizing source83. As before, the output of the gate 86 initiates the generation ofhigh frequency pulses from the pulse generator 87 which are counted bythe counter 88.

It is contemplated that this invention be construed broadly,

as many variants, within the scope of this invention, will suggestthemselves to those in the art.

What is claimed is: l. A method of dimensional measurement of a pattern,

comprising:

televising said pattern to produce a video signal thereof, and

displaying said pattern on a television monitor;

generating an electronic waveform representing a measuring raster, andsuperimposing said raster on said monitor;

varying the waveform so that said raster overlaps at least one dimensionof the pattern to be measured;

producing a series of uniformly timed pulses in response to thecoincidence of (a) the video signal of said pattern exceeding a fixedthreshold value and (b) the electronic waveform representing the rasterexceeding a nominal value, said uniformly timed pulses occurring at afrequency substantially greater than the frequency of the horizontalsweep; and

counting the number of pulses produced during an integral number offrames, said integral number being greater than one, to indicate thedimensional measurement of the pattern.

2. A method of measuring the linear dimension of a shaped configurationcomprising:

televising the configuration to produce a composite video signal inaccordance therewith, and displaying a replica of said configuration ona cathode-ray tube; generating a variable signal representing ameasuring raster, in synchronism with said video signal, forsuperposition with the displayed configuration on said cathode-ray tube,said raster having controllable top, bottom, left, and right marginswith at least two horizontal lines between the top and bottom margins;adjusting the variable signal so that said raster overlaps at least onedimension of the configuration to be measured; producing a series ofuniformly timed pulses in response to the coincidence of a. said videosignal exceeding a fixed threshold value,

with b. the variable signal exceeding a minimal value, said uniformlytimed pulses occurring at a frequency substantially greater than thefrequency of the horizontal sweep; and counting the number of pulsesproduced during an integral number of frames to indicate the dimensionalmeasurement of the pattern. 3. The method as recited in claim 2 whereinsaid measuring raster for superposition on said cathode-ray tube isgenerated by:

coupling a vertical synchronization signal, which is characterized by awaveform having a leading edge which goes from a first level to a secondlevel and a trailing edge which goes back from said second level to saidfirst level, to a first variable pulse width one-shot multi-vibratorwhich is activated by the trailing edge of a signal applied to an inputthereof, the duration of the pulse produced by said first multivibratorbeing variable so as to determine the topmost boundary of the raster;

coupling an output from said first variable pulse width oneshotmultivibrator to a second pulse width one-shot multivibrator which isadapted to be activated by the trailing edge of a signal applied to aninput thereof, said second one-shot multivibrator being variable so asto determine the bottom boundary of the raster;

coupling an output from said second variable pulse width one-shotmultivibrator to one input of an AND gate having a second input coupledto receive a horizontal synchronization signal so that the output of theAND gate provides synchronized pulses indicative of the horizontal linesof the raster to be produced, which pulses occur, in synchronizedfashion, at the beginning of each desired line of raster to begenerated;

coupling an output from said AND gate to a third variable pulse withone-shot multivibrator which is activated by the trailing edge of asignal applied to an input thereof, the third multivibrator having apulse duration which is variable so as to determine the left-hand marginof the raster;

coupling an output from said third multivibrator to an input of a fourthvariable pulse width one-shot multivibrator which is activated by thetrailing edge of a signal applied to an input thereof, the fourthmultivibrator being variable so as to determine the right-hand margin ofthe raster; and

combining an output from said fourth multivibrator with the compositevideo signal and coupling the combination thereof to the cathode-raytube.

4. A method of measuring the area of a shaped configuration comprising:

televising the shaped configuration to produce a video signal thereofand displaying the pattern on a cathode-ray tube;

generating a variable signal representing a measuring raster anddisplaying said raster on said tube;

adjusting the variable signal so that the raster completely overlaps theconfiguration to be measured;

producing a series of uniformly timed pulses in response to thecoincidence of a. the video signal of the configuration exceeding afixed threshold value with b. the variable signal representing theraster exceeding a nominal value;

said uniformly timed pulses occurring at a frequency substantiallygreater than the frequency of the horizontal sweep; and

counting the number of pulses produced during an integral number offrames to indicate the area of the configuration.

5. Apparatus for dimensional measurement of a pattern,

comprising:

means for televising said pattern to produce a video signal thereof, anddisplaying said pattern on a television monitor;

means for generating a variable signal representing a measuring raster,and superimposing said raster on said pattern of said monitor;

means for adjusting the variable signal so that said raster overlaps atleast one dimension of the pattern to be measured;

means for producing a series of uniformly timed pulses in response tothe coincidence of (a) the video signal of said pattern exceeding afixed threshold value and (b) the variable signal representing theraster exceeding a nominal value, said uniformly timed pulses occurringat a frequency substantially greater than the frequency of thehorizontal sweep; and

means for counting the number of pulses produced during an integralnumber of frames, said integral number being greater than one, toindicate the dimensional measurement of the pattern.

6. Apparatus for dimensional measurement, comprising:

a television camera for generating a video signal of an object to beviewed together with appropriate horizontal and vertical synchronizingsignals;

a cathode-ray tube having horizontal and vertical deflection meansassociated therewith, and having a video electrode;

means, synchronized with said horizontal and vertical signals, forgenerating a measuring raster signal to provide a raster controlled asto top, bottom, left, and right margins with two or more horizontallines between the top and bottom margins;

means for coupling the signal from said raster generating means togetherwith the video signal generated by said television camera through thevideo electrode of said cathode-ray tube;

an AND gate having a first input terminal, a second input terminal, andan output terminal;

means for coupling the horizontal and vertical synchronizing signalsfrom said television camera to the horizontal and vertical deflectionmeans associated with i said cathode-ray tube;

means for coupling the signal from said raster generating means togetherwith the video signal from said television camera to input terminals ofsaid AND gate;

means, coupled to said output terminal, for generating a plurality ofpulses when a signal is present on said output terminal, said pulsesoccurring at a frequency substantially greater than the frequency of thehorizontal synchronizing signals; and

means for counting the number of pulses to indicate a dimension of theobject.

7, The apparatus as recited in claim 6 wherein said counting meanscomprises:

a digital pulse counter; and

means for resetting the digital pulse counter after a predeterminedintegral number, greater than one, of vertical synchronization signalsfrom said television camera.

1. A method of dimensional measurement of a pattern, comprising:televising said pattern to produce a video signal thereof, anddisplaying said pattern on a television monitor; generating anelectronic waveform representing a measuring raster, and superimposingsaid raster on said monitor; varying the waveform so that said rasteroverlaps at least one dimension of the pattern to be measured; producinga series of uniformly timed pulses in response to the coincidence of (a)the video signal of said pattern exceeding a fixed threshold value and(b) the electronic waveform representing the raster exceeding a nominalvalue, said uniformly timed pulses occurring at a frequencysubstantially greater than the frequency of the horizontal sweep; andcounting the number of pulses produced during an integral number offrames, said integral number being greater than one, to indicate thedimensional measurement of the pattern.
 2. A method of measuring thelinear dimension of a shaped configuration comprising: televising theconfiguration to produce a composite video signal in accordancetherewith, and displaying a replica of said configuration on acathode-ray tube; generating a variable signal representing a measuringraster, in synchronism with said video signal, for superposition withthe displayed configuration on said cathode-ray tube, said raster havingcontrollable top, bottom, left, and right margins with at least twohorizontal lines between the top and bottom margins; adjusting thevariable signal so that said raster overlaps at least one dimension ofthe configuration to be measured; producing a series of uniformly timedpulses in response to the coincidence of a. said video signal exceedinga fixed threshold value, with b. the variable signal exceeding a minimalvalue, said uniformly timed pulses occurring at a frequencysubstantially greater than the frequency of the horizontal sweep; andcounting the number of pulses produced during an integral number offrames to indicate the dimensional measurement of the pattern.
 3. Themethod as recited in claim 2 wherein said measuring raster forsuperposition on said cathode-ray tube is generated by: coupling avertical synchronization signal, which is characterized by a waveformhaving a leading edge which goes from a first level to a second leveland a trailing edge which goes back from said second level to said firstlevel, to a first variable pulse width one-shot multi-vibrator which isactivated by the trailing edge of a signal applied to an input thereof,the duration of the pulse produced by said first multivibrator beingvariable so as to determine the topmost boundary of the raster; couplingan output from said first variable pulse width one-shot multivibrator toa second pulse width one-shot multivibrator which is adapted to beactivated by the trailing edge of a signal applied to an input thereof,said second one-shot multivibrator being variable so as to determine thebottom boundary of the raster; coupling an output from said secondvariable pulse width one-shot multivibrator to one input of an AND gatehaving a second input coupled to receive a horizontal synchronizationsignal so that the output of the AND gate provides synchronized pulsesindicative of the horizontal lines of the raster to be produced, whichpulses occur, in synchronized fashion, at the beginning of each desiredline of raster to be generated; coupling an output from said AND gate toa third variable pulse with one-shot multivibrator which is activated bythe trailing edge of a signal applied to an input thereof, the thirdmultivibrator having a pulse duration which is variable so as todetermine the left-hand margin of the raster; coupling an output fromsaid third multivibrator to an input of a fourth variable pulse widthone-shot multivibrator whicH is activated by the trailing edge of asignal applied to an input thereof, the fourth multivibrator beingvariable so as to determine the right-hand margin of the raster; andcombining an output from said fourth multivibrator with the compositevideo signal and coupling the combination thereof to the cathode-raytube.
 4. A method of measuring the area of a shaped configurationcomprising: televising the shaped configuration to produce a videosignal thereof and displaying the pattern on a cathode-ray tube;generating a variable signal representing a measuring raster anddisplaying said raster on said tube; adjusting the variable signal sothat the raster completely overlaps the configuration to be measured;producing a series of uniformly timed pulses in response to thecoincidence of a. the video signal of the configuration exceeding afixed threshold value with b. the variable signal representing theraster exceeding a nominal value; said uniformly timed pulses occurringat a frequency substantially greater than the frequency of thehorizontal sweep; and counting the number of pulses produced during anintegral number of frames to indicate the area of the configuration. 5.Apparatus for dimensional measurement of a pattern, comprising: meansfor televising said pattern to produce a video signal thereof, anddisplaying said pattern on a television monitor; means for generating avariable signal representing a measuring raster, and superimposing saidraster on said pattern of said monitor; means for adjusting the variablesignal so that said raster overlaps at least one dimension of thepattern to be measured; means for producing a series of uniformly timedpulses in response to the coincidence of (a) the video signal of saidpattern exceeding a fixed threshold value and (b) the variable signalrepresenting the raster exceeding a nominal value, said uniformly timedpulses occurring at a frequency substantially greater than the frequencyof the horizontal sweep; and means for counting the number of pulsesproduced during an integral number of frames, said integral number beinggreater than one, to indicate the dimensional measurement of thepattern.
 6. Apparatus for dimensional measurement, comprising: atelevision camera for generating a video signal of an object to beviewed together with appropriate horizontal and vertical synchronizingsignals; a cathode-ray tube having horizontal and vertical deflectionmeans associated therewith, and having a video electrode; means,synchronized with said horizontal and vertical signals, for generating ameasuring raster signal to provide a raster controlled as to top,bottom, left, and right margins with two or more horizontal linesbetween the top and bottom margins; means for coupling the signal fromsaid raster generating means together with the video signal generated bysaid television camera through the video electrode of said cathode-raytube; an AND gate having a first input terminal, a second inputterminal, and an output terminal; means for coupling the horizontal andvertical synchronizing signals from said television camera to thehorizontal and vertical deflection means associated with saidcathode-ray tube; means for coupling the signal from said rastergenerating means together with the video signal from said televisioncamera to input terminals of said AND gate; means, coupled to saidoutput terminal, for generating a plurality of pulses when a signal ispresent on said output terminal, said pulses occurring at a frequencysubstantially greater than the frequency of the horizontal synchronizingsignals; and means for counting the number of pulses to indicate adimension of the object.
 7. The apparatus as recited in claim 6 whereinsaid counting means comprises: a digital pulse counter; and means forresetting the digital pulse counter after a predetermined integralnumber, greater than one, of vertical synchronization signals from saidtelevision camera.